Highly efficient and automated extraction of DNA from human remains using a modified EZ1 protocol

Bones and teeth often represent the only sources of DNA available for identifying human remains. DNA in bones and teeth is generally better preserved than that in soft tissues because of the presence of hard connective tissue with a high level of calcium. Because of the extensive mineralisation, the choice of an efficient DNA extraction procedure is important to minimise the sampling of a high level of minerals and to remove polymerase chain reaction (PCR) inhibitors. Some protocols are available for DNA extraction from bones and teeth as part of the Qiagen EZ1 DNA Investigator Kit using the EZ1 Advanced XL automated purification platform. To improve the efficiency of DNA extraction from skeletal remains, the present study focuses on a modification to these already available protocols. In this study, different bones and teeth collected between 1 and 50 years after death were subjected to DNA extraction using the standard EZ1 protocol, a supplementary protocol, and a modified protocol. The modified approach included a decalcification step, whereas the Qiagen protocols worked directly on non-decalcified powder. In all three procedures, 150 mg samples were used for DNA extraction. We evaluated the quantity of DNA recovered from samples, the presence of any PCR inhibitors co-extracted, the level of DNA degradation, the quality of short tandem repeat (STR) profiles, and the reproducibility of the modified procedure. When compared with the other protocols, the modified protocol resulted in the best recovery of DNA that was free of PCR inhibitors. Additionally, the STR profiles were reliable and of high quality. In our opinion, the decalcification step increases DNA recovery by softening tissues, which allows lysis solutions to act more effectively. Furthermore, the use of two lysis solutions and the variation added to the EZ1 purification step allow for DNA recovery with quality and quantity superior to those of the previously available Qiagen-based protocols. These findings may be helpful solutions to the problems commonly encountered when dealing with difficult samples, such as bones and teeth.

Key points

• Bones and teeth often represent the only sources of DNA for identifying human remains.
• The choice of an efficient DNA extraction procedure is important for maximizing DNA recovery and removing PCR inhibitors.
• This study focuses on modifications to the previously available Qiagen-based protocols.
• The modified protocol enabled the best recovery of DNA, and both quality and quantity were superior to those of the previously available Qiagen-based protocols.
• The STR profiles obtained from samples extracted using the modified protocol were reliable and of high quality.

     

Illuminating the benefits and limitations of forensic light sources

Forensic light sources, such as a Crime-lite, are used in forensic laboratories and by police staff in the examination for, and detection of, biological material. Whilst the benefits of using forensic light sources are relatively well understood, their limitations are less-so. This report details the outcome of studies, validation and review by three forensic laboratories, as well as three case examples, to highlight both the strengths and weaknesses of the tested forensic light sources and to demonstrate that, whilst a useful preliminary screening tool, they should not be used in isolation without subsequent presumptive chemical testing. False positives and negatives are common, and the background substrate and specific biological material present can have a significant effect on the outcome of examination when using a forensic light source.     

CHN骨龄在司法鉴定中的应用价值

目的探讨CHN(中国人手腕骨发育标准CHN法)骨龄在司法鉴定中的应用价值,分析影响其准确性的因素及相关问题。方法对522例年龄鉴定者,均选用不同曝光值拍摄两张左手腕部正位X线片,并加照两次斜位片。使用CHN法测评骨龄。结果522例中男性489例,女性33例。男性达CHN骨龄最高值18.4岁者129例,余平均骨龄16.5岁。女性达CHN骨龄最高值17.3岁者14例,余平均骨龄15.7岁。CHN骨龄在16.0岁以上者共388例,占约74.3%。本组资料显示多种因素影响骨龄鉴定的准确性,其中以骨龄片位置及角度的变化等影响最大。结论如能获得高质量的X线片、并能熟练使用CHN法、注意利用位置和角度的变化正确判定骨骺分级,CHN骨龄基本可满足活体年龄鉴定的需要。     

侦查错误界定标准的基本问题研究

目前各种关于侦查错误的界定标准,虽然在某种程度上促进或丰富了侦查错误理论的发展,但是部分界定标准不符合法理或者不适用于现阶段我国关于侦查错误的理论与实践。因此,应在通过对各种侦查错误界定标准的分析和检视定位的基础之上,重新构建适合于我国的侦查错误的界定标准。     

我国刑事诉讼专家辅助人制度探析

由于缺乏相应的科学技术和专门性知识,诉讼当事人和司法人员不能对刑事诉讼鉴定意见进行科学评判。专家辅助人制度能够很好地解决鉴定意见在司法实践中存在的问题。但目前法律对专家辅助人制度规定得过于原则和粗糙,缺乏具体程序规范,这必然会给司法实践带来诸多困难。本文以专家辅助人制度的功能为逻辑出发点。探析了该制度的基础理论、运行规则以及相关的配套制度。     

行政法开放性之思考

行政法应当是一个开放的系统,即对其他社会现象、社会过程、社会关系、治理系统等都是开放的。行政法开放性既是客观的又是必然的,是当代行政法的发展趋势。行政法的开放性有着非常深刻的法治价值,它具有技术规则的吸收功能、公众需求的满足功能、新型社会关系的认同功能、后信息化社会的适应功能。然而,我国行政法在开放性方面是受到阻滞的,可以说还处于相对封闭的状态之下。因此,必须在行政法理论基础、行政法治体系、行政法的实施和行政法的实现等环节上有所突破,重构我国行政法治体系的思路：区分和定位行政法软件与硬件、确立行政法纲领性与规范性的目标选择、合理分类行政法恒定规则与过渡规则、注重行政法输入要素与输出要素的关系转换。     

浅谈“中国模式”的存在性及重构——基于中国特色社会主义视角的思考

近年来,＂中国模式＂成为国内外学者关注的重要课题。尤其是2008年全球金融危机爆发,资本主义国家遭受重创,而中国却仍能保持经济的平稳快速增长,因此众多学者纷纷将目光转向中国,试图从中挖掘出拯救国内危机的良方。中国特色社会主义为我们解读中国模式确立了一个合理的视角和范式,从这里出发,我们可以对诸如＂中国模式＂与中国特色社会主义的关系及其重构问题作出合理的辨析。     

困境与出路：刑事执行检察工作现状与重构

为适应形势的需要,最高人民检察院将传统“监所检察”变更为“刑事执行检察”。这一变更不是简单的部门称谓的变化,而是涉及工作职责、工作方式、工作理念的重大变化。但是,现实中还存在法律支撑不足、工作机制不健全、机构设置不合理、人员力量有限、监督角色被同化等诸多与刑事执行检察发展不相适应的地方。笔者通过对当前以派驻检察为主的刑事执行检察工作现状的分析,试图找出解决制约工作发展的障碍,寻求刑事执行检察工作科学发展的出路。     

乌头碱对培养新生大鼠心室肌细胞Connexin43蛋白磷酸化的影响

目的建立细胞水平的染毒模型,观察乌头碱对心肌细胞缝隙连接蛋白Connexin43(Cx43)的影响。方法实验分0.25、0.5、0.75、1.0、1.5和2.0μmol/L等6个不同浓度乌头碱染毒组,运用蛋白印迹法和免疫荧光技术,检测各组及对照组心肌细胞Cx43蛋白磷酸化状态的改变。结果蛋白印迹检测显示,不同浓度染毒组心肌细胞中Cx43蛋白总量与正常对照组无显著差异;0.5μmol/L乌头碱染毒后,Cx43开始出现脱磷酸化;当染毒浓度达到1.0μmol/L后,Cx43脱磷酸化显著,且1.5及2.0μmol/L染毒效果和1.0μmol/L染毒组相当。免疫荧光分析结果提示乌头碱作用后,心肌细胞Cx43蛋白在羧基端第368位点丝氨酸残基(Ser368)发生明显的脱磷酸化。结论一定浓度的乌头碱能诱导心肌细胞缝隙连接蛋白Cx43发生显著脱磷酸化。     

交通事故伤亡人员的法医病理检验

近年来,交通事故发生率急剧上升,事故中的死亡人数逐年上升,本文通过对笔者在多年的交通事故处理中的经验总结和实践探讨的阐述,说明在交通事故中对尸体进行法医病理检验的重要性和必要性。